2,5-dihydroxy-monomethyl- or -diethylamino benzene and the salts thereof



United States Patent 874,11 Int. Cl. A61k 7/12,- C07c 91/18, 91/42 US. Cl. 260-574 4 Claims ABSTRACT OF THE DISCLOSURE Dye compounds having improved chemical and color stability selected from the group consisting of 2,5-dihydroxy-mono and dialkyl amino benzene, said alkyl groups having up to 4 carbon atoms.

This application is a continuation-in-part division application of application Ser. No. 207,090, filed July 2, 1962, and now abandoned.

This invention relates to compounds for dyeing hair, furs, and other keratinous fibers.

The known hair-dyeing processes are based almost exclusively upon the use of a mixture of aromatic paradiamines and aminophenols, that is to say, on the use of intermediate bases which are converted by oxidation to dyes which have a true dyeing action on the fiber, with the aid of modifiers such as metadiamines and phenols or polyphenols.

The formation, from these mixtures, of the coloring matter which has the dyeing effect results from a series of very complex chemical reactions. The method necessitates, on the one hand, the use of an oxidizing substance, such as hydrogen peroxide, and the presence of a base, such as an alkali hydroxide, ammonia, etc. Consequently, the pH of these dyeing compositions is usually between 9 and 10.

The aforesaid processes, which are entirely satisfactory from the viewpoint of the dyes and of the shades obtained, nevertheless have some disadvantages. More especially, the use of paradiamines may sometimes result in slight dermatitis and may produce allergies in some particularly sensitive persons. Moreover, in these processes, the solution of the dyes is usually mixed, a few instants before use, with a dilute hydrogen peroxide solution and the mixture is applied to the hair. This addition constitutes a complication and is a cause of degradation of the keratin of the hair. The alkali which is present in these dyeing compositions may also give rise to hydrolysis and deterioration of the texture of the hair.

US. Pat. 3,011,858 describes a process for dyeing live human hair, fur and other keratinous fibers which comprises impregnating the fibers with an aqueous solution of at least one dihydroxyaminobenzene selected from 2,S-dihydroxyaminobenzene, 2,4-dihydroxyaminobenzene and 3,4-dihydroxyaminobenzene, and acid addition salts thereof, and subjecting the impregnated fibers to the action of an oxidizing agent. It has been possible by this process to obviate or greatly to lessen, the aforesaid disadvantages.

Using the aforesaid compounds the allergic manifestations are greatly reduced and the use of hydrogen peroxide and alkali is unnecessary. It is possible to obtain attractive shades by application of aqueous solutions of these products at a pH value of 7, without any additional oxidizing agent, by simple exposure to the ambient air. However, in the commercial utilization of these products it has been found that aqueous solutions of 2,4-dihydroxyaminoben- 3,546,294 Patented Dec. 8, 1970 zene and of 3,4-dihydroxyaminobenzene have an inconvenient color instability even at a pH of 7, and that their dyeing power decreases and may even disappear at the end of several months.

It has surprisingly now been found that aqueous solutions of certain 2,S-dihydroxyaminobenzene derivatives not only remain stable and do not lose their dyeing properties, but in addition make it possible to produce particularly valuable shades of coloration of the fibers. This is important since it is well known to be essential in this art to have available a range of compounds capable of producing different variations of shade.

According to the present invention there is provided new compounds for dyeing live human hair, fur or other keratinous fibers which comprises impregnating said fibers with an aqueous solution of at least one compound set forth below, and causing or allowing oxidation of the compound to take place on the fibers.

In a particularly convenient method of carrying out the dyeing process using the compounds of the invention, the hair, fur or other keratinous fiber is impregnated with an aqueous solution containing at least one compound of the above general formula, in contact with the air, the pH of the solution being between approximately 3 and 10. The results are particularly satisfactory when the pH of the solution is approximately 7.

New compounds of the above general formula which are particularly suitable for carrying out the process of the invention are: 2,S-dihydroxy-monomethylaminobenzene, 2,5-dihydroxy-diethylaminobenzene and 2,5-dihydroxy- B-diethylaminoethyl -aminobenzene.

It will be noted that the method just described using these compounds does not require the addition of an oxidizing agent, or the provision of alkali because these compounds may be oxidized by the oxygen in the air. Moreover, the compounds used have not been found to give rise to allergic reactions in the subjects when applied to human hair.

It is, however, possible when desired to use an oxidizing agent, for example hydrogen peroxide or any oxidizing agent used in this art, and a base, such as an alkali hydroxide, ammonia, etc., in order to increase the pH of the dyeing solution. The results are also satisfactory and the colors remain stable.

It is also possible to add to the aqueous dyeing compositions of this invention the conventional employed in hair dyeing and intended to increase the yield or to produce other effects, such as, for example, wetting agents, thickening agents, foaming agents, and reducing agents such as sodium sulphite.

The compounds 2,5 dihydroXy-monomethylaminoben zene, 2,S-dihydroxy-diethylaminobenzene and 2,5-dihydroxy-(fi-diethylaminoethyl)aminobenzene are novel per se and the invention includes these compounds and the processes for their production, referred to later herein, and also dyeing compositions containing them.

The following examples will serve to illustrate the invention.

(A) EXAMPLES OF PREPARATION 1) 2,5 -dihydroxy-monomethylaminobenzene (a) Preparation of 2,5-dimethoxy N methylacetanilide.-The corresponding sodamide is prepared in the usual way by introducing 6.32 gram-atoms of sodium into an excess of liquid ammonia. 5.05 mol of 2,5-dimethoxyacetanilide are then introduced in small portions. The mixture is allowed to stand for 1 hour and 6.56 mol of methyl sulphate are then introduced over a period of 1 hour. The excess of ammonia is then allowed to evaporate. The remaining residue is taken up in water and extracted with methylisobutylketone. After evaporation of the solvent there is obtained, in a yield of 92.5%, an

oily product corresponding to the desired product, which is directly treated without further purification.

(b) Preparation of the hydrobromide of 2,5-dihydroxymonomethylaminobenzene.A mixture of 4.66 mol of 2,5-dimethoxy-N-methyl-acetanilide and 7 litres of 48% hydrobromic acid is refluxed for 4 hours. The product is thereafter concentrated by evaporation in vacuo, in a nitrogen atmosphere, to about 1.3 litres. The products precipitate on cooling in a mixture of ice and salt. After separation and drying in vacuo at 100 C., the desired hydrobromide is obtained in a yield of 77%. After recrystallization from hydrobromic acid, this product melts at 177-178 C. with decomposition.

Analysis.-Calcd for C H NO Br (percent): C, 38.19; H, 4.54; N, 6.36. Found (percent): C, 37.72-37.83; H, 4.45-4.53; N, 6.44.

(2) 2,5-dihydroxydiethylaminobenzene (a) Preparation of 2,5-dimethoxy-diethylaniline.A mixture of 0.2 mol of ethyl phosphate and 0.2 mol of 2,5-dimethoxyaniline is heated under reflux for 4 hours. After cooling to 70 C., the mixture is poured into 200 cc. of 13% sodium hydroxide. The whole is refluxed for one and a half hours and, after cooling and dilution with water, extraction is effected with diethyl ether. The product obtained is distilled in vacuo and passes over at 71- 7 8 C. under 0.07 mm. Hg pressure. The yield is 75%.

(b) Preparation of 2,5 dihydroxy diethylaminobenzene.A mixture of 0.15 mol of 2,5-dimethoxy-diethy1- aniline, 34 cc. of glacial acetic acid and 250 cc. of 65% hydrobromic acid is heated under reflux for 4 hours. The reaction mixture is thereafter evaporated in vacuo and under a nitrogen atmosphere. The desired product is thus obtained in a quantitative yield. The 2,5-dihydroxydiethylaminobenzene hydrobromide is purified by dissolution in absolute ethanol and reprecipitation by means of diethyl ether. It is a hygroscopic product.

Analysis.Calcd for C H O NBr (percent): C, 45.80; H, 6.10; N, 5.34. Found (percent): C, 45.54; H, 6.31; N, 5.15.

(3) Preparation of 2,5-dihydroxy-(B-diethylaminoethyl) aminobenzene (a) Preparation of 2,5 dimethoxy (fl-diethylaminoethyl)-aminobenzene.-A solution of 1.75 mol of the hydrochloride of N-fi-diethylaminoethyl chloride in 800 cc. of water is added over a period of 2 hours to a mixture, maintained at boiling point, of 1.63 mol of 2,5-dimethoxy-aniline, 0.95 mol of calcium carbonate and 2.5 litres of water. After cooling and extraction with methylisobutylketone to remove the unconverted products, the reaction mixture is made alkaline by the addition of 200 g. of 40% sodium hydroxide and again extracted with methylisobutylketone. The product is distilled in vacuo. It passes over at 130-135 C. under 0.1 mm. Hg pressure. The yield is of the order of 78%.

(b) Preparation of 2,5 dihydroxy (,8 diethylaminoethyl)-aminobenzene.A mixture of 1.3 mol of 2,5-dimethoxy (B diethylaminoethyl)-aminobenzene and 1.5 litres of 48% hydrobromic acid is heated under reflux for 2 hours. After evaporation to dryness in vacuo and under a nitrogen atmosphere, the dihydrobromide of 2,5-dihydroxy-(,B-diethylaminoethyl)-aminobenzene is obtained in a quantitative yield. The product thus obtained is purified by dissolution in absolute ethanol and reprecipitation by means of ether. The product is very hygroscopic.

Analysis.Calcd for C H O N Br (percent): C, 37.30; H, 5.69; N, 7.25. Found (percent): C, 37.08-37.22; H, 5.68-5.99; N, 7.28.

4 (B) EXAMPLES OF THE APPLICATION OF THE DYEING COMPOSITIONS Example I The following solution is prepared:

2,S-dihydroxy-methylaminobenzene hydrobromide-2.2 g.

Fatty alcohol C -C condensed with 2 mol of ethylene oxide, sulphated, sodium salt containing 20% of initial hydroxy-ethylenated alcohol4 g.

5 N sodium hydroxide solution, q.s. for pH 7.

Water, q.s. for cc.

This solution is applied to grey hair and left in contact with the air for 20 minutes. After rinsing and drying the hair has a pale golden shade.

Example 11 In the same way as Example I, there is prepared a solution containing:

2,S-dihydroxy-diethylaminobenzene hydrobromide-3 g.

Fatty alcohol C12-C14 condensed with 2 mol. of ethylene oxide, sulphated, sodium salt containing 20% of initial hydroxy-ethylenated alcohol4 g.

5 N sodium hydroxide solution, q.s. for pH 7.

Water, q.s. for 100 cc.

When this solution is applied to grey hair for 20 minutes, and then rinsed and dried, a pink-tinged light blond shade is obtained.

Example III When, under the same conditions as in Example II, there is applied to the hair a solution prepared from:

A very natural blond shade is obtained on grey hair. What is claimed is:

1. 2,5-dihydroxy-monomethylaminobenzene.

2. An acid addition salt of the compound of claim 1. 3. 2,5-dihydroxy-diethylaminobenzene.

4. An acid addition salt of the compound of claim 3.

References Cited UNITED STATES PATENTS 3,011,858 12/1961 Lantz et al 167-88X 3,214,472 10/1965 Charle et a1. 260-57l 3,236,734 2/1966 Charle et al 167-88 FOREIGN PATENTS 1,222,700 1/ 1960 France 260574 OTHER REFERENCES Chemical Abstracts, vol. 26, pp. 4062-63 (1932), abstract of German Pat. No. 550,327.

Chemical Abstracts, vol. 26, p. 7594 (1932).

Martynotf et al.: Bull. Soc. Chim. France, 1947, pp. 52-53.

ROBERT V. HINES, Primary Examiner US. Cl. X.R. 

